Doubletree.



PATENTED MAY 10. 1904.

A. J. GRAY.

DOUBLETREE.

APPLIUATION FILED JULY 2o, 1903.

2 SHEETS--SHEET l.

im MODEL.

WIT 45,353'

me norms mens co, uovo-Mmc.. msnmaon n c PATENTED MAY l0, 1904.

A. J. GRAY.

DOUBLETREE.

APPLIUATION FILED JULY zo, 1903.

2 SHEETS-SHEET 2.

NO MODEL.

/fnesse .7/. @a .L

UNITED STATES Patented May 10, 1904.

PATENT OEEICE.

ALMON J. GRAY, OE ST. PAUL, MINNESOTA, ASSIGNOR OE ONE-HALF TO GEORGE A. DAY, OE MINNEAPOLIS, MINNESOTA.

DOUBLETREE.

SPECIFICATION forming part of Letters Patent No. 759,267, dated May 10, 1904.

Application filed July 20, 1903. Serial No. 166,283. (No model.)

To r/,ZZ whom it 71u14/ concern.:

Beit known that I, ALMON J. GRAY, of St. Paul, county of Ramsey, State of Minnesota, have invented certain new and useful Improvements in i)oubleti'ees, of which the following' is a specification.

The object of my invention is to provide an improved doubletree that is protected and strengthened where it is subjected to Wear and 1o the greatest strain.

A further object is to provide a doubletree having means for distributing the strain of the resistance offered by the load when it is started or obstructed and to take the jar oif the shoulders of the horses when the load meets unusual obstructions and to graduate the strain which these obstructions usually put upon the vehicle being drawn-and the harness, thus lessening unnecessary breakages and 2o other damage to vehicles and injuries to the horses.

A further object is to provide means for distributing the strain, as aforesaid, which will yield slightly under a slight pull and continue to yield under a greater pull, the resistance increasing' in proportion to the increased strain.

A further object is to provide means for adjusting' said yielding means to vary its tension according to the character of the werk where 3o used.

The invention consists generally in various constructions and combinations, all as hereinafter described, and particularly pointed out in the claims.

In the accompanying drawings, forming part of this specification, Figure l is a plan view of a doubletree embodying' my invention. Fig. 2 is a plan section. Fig. 3 is a section on the line e .fr of Eig'. 2. Fig. l is a detail section showing a modified construction. Fig. 5 is a section on the line 1/ y of Eig 4.. Eig. 6 is a detail of one end of the doubletree, showing a modilied form of a protecting-plate thereon. Eig. 7 is a similar View showing' still another construction and also-showing the bell-crank device pivotally.supported at the end of the doubletree. Fig. 8 is a similar View showing a strap or band secured to the `end of the doubletree. Eig. 9 is a detail View of one end of the doubletree, showing the springs under tension.

In the drawings, 2 represents a wooden doubletree provided at its center with a metal box or frame 3, that may be made of malleable casting in one piece or sheet metal, as preferred, and preferably longer in front than in the rear to provide an additional bearingsurfaee, as plainly shown in Fig. 1.` This box receives the doubletree and is preferably wider at one end than at the other and provided at a point intermediate to its ends, preferably in its forward wall, with a transverse rib A, that is adapted to enter a correspondingly-shaped groove in the forward edge of the doubletree. This box is suliiciently loose on the doubletree when placed thereon to allow the rib to slip easily into the groove, and the box is then clamped securely by means of a wedge 5, that is inserted between the rear wall of the box and the rear edge of the doubletree. (See Eig. Q.) When this wedge is driven firmly in place, the front wall will be drawn against the doubletree, the rib will be forced therein, and the box will be locked on the doubletree and will be prevented from slipping by the said 75 rib. The long bearing-surface ofthe box on the forward edge of the doubletree strengthens the same at this point and also prevents it from wear resulting from contact with the swingletrees. The manner of securing the box in place by wedging renders it easily attachable and readily removable and also braces the doubletree.

The rear wall of the box 3 is provided with rearwardly-extending lugs 6, having' counter- 35 sunk holes 7 to receive correspondingly-shaped nuts 8 on threaded bolts 9, that are adjustable in said holes to vary the tension of the springs. These lugs extend back as far as practicable and in connection with the springs serve to 90 brace and strengthen the doubletree. Between the lugs 6 I prefer to provide a loop or eye 10, that is preferably cast integrally with the lugs and with said box, though the lugs and loop may be made independently of the box,ifI preferred, 95 and secured thereto. The draw-bolt of a wagon or other vehicle may be slipped through the loop to secure the doubletree thereto, and said loop is also adapted to receive a hook, chain, or other draft appliance provided between the doubletree and the load. This loop takes the place of the eye or staple provided on some doubletrees at this point and usually secured b v bolts. It also dispenses with the clevis when the doubletree is used on a lead team or elsewhere when there is no other means of attachment provided. r1`hese staple-securing' bolts necessarily weaken the doubletree at this point. By providing a means of attachment which dispenses with these bolts and brings the strain upon the wood at its front edg'e I am able to provide a doubletree that will have the strength of the full length of the wood reinforced by the metal box and will be equally7 strong at all points, and hence can be made of comparatively small dimensions and of light inexpensive wood and still be sufficiently strong to stand all strain to which it may be subjected. The use of the loop also renders it unnecessary to have a hole through the center of the doubletree for the'draw-bolt. I may, however, make provision for such a hole, and when a bolt is used it passes through the top and bottom walls of the metal box against which it bears, and as the wood is wedged within the box and pressed by the walls thereof it will not be materially weakened by the formation of the bolt-hole.

In Fig. 4 I have shown a modified form of box for the center of the doubletree, consisting of a sheet-metal casing 10, having inwardly-turned lips or anges 11 on its forward wall that are adapted to enter saw-slits in the forward edge of the doubletree and prevent the casing from slipping out of its proper place thereon. The side walls of the casing extend back over the top and bottom of the doubletree, and the edges of said walls are bent around the corners of the rear edge of the doubletree and are secured by rivets 12 to a plate 13, that forms the rear wall of the casing. The inner surface of the plate 13 is tapered or inclined, causing the said plate to be thicker at one end than at the other, as indicated in Fig. 4, and when the casing is slipped onto the doubletree there will be sufhcient freedom of movement to allow the lips 11 to slip into the saw-slits, and when this has been done a wedge similar to the one heretofore described is inserted between the said plate 13 and the rear edge of the doubletree until its ends are fiush substantially with the ends of said plate. The plate may be provided with holes to receive screws 14, which, passing' down through the ends of the wedge and into the doubletree, secure the former in place and prevent its accidental displacement and the loosening of the casing. The plate 18 is provided with the rearwardly-extending lugs heretofore described and also with the integral loop between them.

The metal box may be made, if preferred, with its front and rear walls parallel, omitting the rib on the correspondingly-shaped notch in the doubletree, in which case the box would be fitted snugly on the center of the doubletree and secured thereto by screws or other suitable means.

The ends of the doubletree are rounded, as shown, and provided with protecting metal bands 15 and bell-cranks 16, having integral arms 17, that are pivotally secured to the ends of said doubletree by bolts 18. The forward arm 19 of each bell-crank is provided with a series of holes 20, to which the swingletree-clevis 21 is attached in the usual way. The rear of each bell-crank when in its normal position bears on the end of the band 15, and is'thereby prevented from wearing the wood of the doubletree. The other arm 22 of the bell-crank is provided with a series of notches 23, and a hook 24 is provided with a slot 25 to receive the said arm 22, and said slot has an edge 26 to enter the notches 23 and permit the convenient adjustment of the hook on said arm, according to the character of the work where the doubletree is used and the desired leverage on the spring. As the crank is swung forward the hook becomes wedged on its crankarm (see Fig. 9) and extends out from it substantially at right angles, holding the spring out of contact with the arm and slightly increasing its extension.

27 is a closely-coiled spring having a loop 28 at one end to engage the hook 24 and contracted at its opposite end to an opening of sufhcient size only to receive the bolt 9 and allow it to slide freely therein, the headed end of said bolt being inclosed by said spring and too large to pass through the open end thereof. A smaller lighter spring 29 is coiled upon the said bolt and is arranged to be compressed between its head and the contracted end of the spring 27 when power is applied to extend the spring' 27. It will therefore happen that in drawing an empty wagon or a light load the springs 29 at each end of the doubletree will be compressed in starting the load, or when meeting a slight obstruction or upon an incline while under ordinary conditions the heavy springs 27 will not be affected. 1f, however, sufcient power is applied to the bell-cranks to compress the springs 29 to their limit when further power is applied, as in moving a heavy load, the springs 27 will be extended in proportion to the strain placed upon them. The large springs will admit safely of an extension of five or six inches, and the use of two springs, one within the other, permits a greater range of movement and adapts the doubletree for use with a light or heavy load. The opening in the tapered end .LOO

IIO

of the large spring will allow the bolt-shank to slide therein, though not being' of sufficient size to permit the passage of the bolt-header the inner spring 29, which is preferably squared to provide a better bearing against the inside of the tapered end of the large spring. The small springs are preferably arranged to be compressed with a strain of about two hundred pounds land have about two inches of compression. These springs will yield when an obstruction is met or when the team jumps or plunges, so that all danger ofbreakages through any sudden strain is entirely avoided. The use of the two springs not only prevents damage to the doubletree, but saves the horses, harness, swingletree, and even the vehicle itself from injury.

ln Fig. 6 I have shown a modified form of a box or casing at the ends of the doubletree which consists in a casting 30, formed to lit the beveled ends 3l of the doubletree and having dovetailed ribs 32, that are adapted to enter correspondingly-shaped slots 33, arranged transversely of the forward and rear edges of the doubletree. A lug 34C is formed integrail y with the casting 30 at its outer end and having a hole to receive a bolt 35, forming a pivot for the bell-crank 36. This bell-crank is arranged to bear on the inclined portion of the box 30, covering the beveled end of the doubletree, and is limited in its backward movement by said surface, as shown in Fig. 7. The rear arm is normally substantially at right angles to the spring, the tension of which will prevent the hook, to which the sp1-i ng is connected, from accidentally slipping oif the said arm. The holes in the forward arm of the bell-crank 16 are arranged so that one or more of them when the bell-crank is in its normal position will be back of the point at which the bell-crank is connected to the doubletree. This allows the distance between the points at which the device is attached to the doubletree and the swingletree to be much less than it otherwise would to obtain the shortest leverage and the greatest movement.l The purpose of this arrangement is to obtain the proper relative movement of the swingletree with a maximum extension of the spring without too long an arm on the rear of the bell-crank and to give the forward arm of the bell-crank, to which the swingletree-clevis is attached, a more uniform leverage throughout its entire movement.

The box may be made of malleable casting and is preferably a little narrower than the doubletree, so that it necessary to spring' the ends of the casting outwardly to slip the dovetailed ribs into their slots. When this has been done, however, the casting will firmly grip the end of the doubletree, and the ribs cannot accidentally slip out of place. lf preferred, the dovetailed ribs may be omitted and the ends of the casting merely turned in to form anges to enter correspondinglyshaped slots in the wood.

The box or casing in Fig. 6 is open on the upper and lower sides; butin Fie'. 7 I have shown abox of similar shape having' walls 37, that close the upper and lower sides and form with the front and rear walls a socket that incloses the end of the doubletree. Then the box is made in this form and the spring is connected to the bell-crank, no fastening devices are necessary to hold the box en the doubletree; but l have shown a bolt 38 for securing' the box in place; but it may be omitted, if preferred.

In Fig. 8 I have shown a form of box 39 for the end of the doubletree that is similar to the one shown in Fig. 6, except that the locking-ribs are omitted, a bolt similar to the one shown in Fig. 7 being substituted therefor as a fastening' means.

From the foregoing it will noted that my improved d oubl etree is protected and strengthened wherever it is subjected to wear or strain and is so constructed that it will be sufliciently strong, even when made of comparatively weak wood. This construction also permits a reduction in the usual dimensions required with perfect safety. The device can be readily put together and does not require the service of a skilled mechanic or the use of a large number ,of tools. The double springs, one within the other, have a wide range of movement and adapt the doubletree for use with a light driving-wagon, as well as for heavy teaming. The tension of the springs can be readily changed by means of the adjusting devices to adapt the springs for yielding with a light or heavy strain. One spring within the other permits the use of longer springs, that will give the required movement without impair-ing their efficiency. It will also be noted that the connection between the springs and the bell-cranks allows the leverage of the former to be changed according to the character of the work.

l ith the ends of the doubletree beveled, as shown, and the casing made to fit them the cranks can be arranged across the center of the doubletree ends, and the same movement of the cranks and the places for attachment, with the advantages heretofore explained, are retained. The ease with which this casing is attached and the possibility of using a shorter and lighter bar of wood, as the full width at the end is utilized to resist the strain are some of the advantages of this method of construction.

I claim as my inventionl. In a doubletree, the combination, with a wooden bar, of a box or frame wherein said bar is inserted, a transverse rib provided on said box and adapted to enter a corresponding slot in said bar, said box having sufiieient lateral movement on said bar to allow said rib IOO TIO

to enter said slot, and means for clamping said box on said bar near the center thereof.

2. The combination, with a box or frame, of a wooden doubletree-bar fitting' within said box, means provided on said box to engage said bar and prevent lateral movement of said box thereon, said box being wider at one end than at the other-,and a wedge litting between the wall of said box and bar, for the purpose specified.

3. The combination, with a box or frame provided with a transverse rib, of a doubletree-bar fitting within said box and having a transverse slot to receive said rib, said box being wider at one end than at the other, and a wedge fitting between the rear wall of said box and the rear edge of said bar, substantially as described.

4. The combination, with a doubletree-bar, of bell-cranks pivoted on the ends thereof, lugs provided near the center of said bar, and springs connecting the rear arms of said bellcranks and said lugs respectively, and means for adjusting the tension of said springs, and means for changing the leverage of said bellcranks thereon.

5. rlhe combination, with a doubletree, of bell-cranks pivoted on the ends thereof, springs connected with the rear arms of said bellcranks, means near the middle of the doubletree supporting the inner ends of said springs, and means for adjusting' the outer ends of said springs on said bell-crank arms toward or from said doubletree to vary the leverage of the bell-cranks on said springs.

6. 'lhe combination, with a doubletree, of bell-cranks pivoted thereon, hooks adjustably arranged on the rear arms of said bell-cranks, springs connected at their outer ends to said hooks, and means for supporting the inner ends of said springs.

7. The combination, with a doubletree, of bell-cranks pivoted on the ends thereof, lugs provided near the center of said bar, springs arranged one within the other and connecting the rear arms of said bell-cranks and said lugs respectively,the inner springs being arranged to act under a light pull exerted on said bellcranls, and the outer springs under a heavy pull, substantially as described.

8. The combination, with a doubletree, of bell-cranks pivoted on the ends thereof, coilsprings connected with the rear arms of said bell-cranks,small springs provided within said first-named springs, means supporting the inner ends of said springs and Ysaid smaller springs being put under tension bythe initial movement of said bell-cranks and said lirstnamed springs by the subsequent movement thereof. y

9. The combination, with a doubletree, of the bell-cranks pivoted on the ends thereof, coiled primary springs connected at their outer ends to the rear arms of said bell-cranks, lugs provided on said doubletree, bolts secured to said lugs and having their headed ends slidable within said springs, and similar secondary springs provided on said bolts between their heads and the inner ends of said first-named springs, substantially as described.

10. The combination, with a doubletree, of

' coiled extension-springs, means pivoted on the ends of said doubletree and connected with the outer ends of said springs and having means for attachment to swingletrees, compressionsprings arranged within said first-named springs, and means for supporting the inner' ends of said compression and extension springs and arranged to put them in tension successively in the order named upon the initial and subsequent movement of said pivoted means, substantially as described.

11. The combination, with a doubletree, of bell-crankspivotally secured to the ends thereof, said bell-cranks having rear arms projecting substantially at right angles to the doubletree, the forward arms of said bell-cranks having holes for attachment to a swingletreeclevis, and said holes being when the bellcrank is in its normal position in the rear of its pivotal connection to said doubletree, springs having their outer ends attached to said rear arms, and means for supporting the inner ends of said springs.

12. The combination, with a doubletree, of bell-cranks pivoted on the ends thereof and comprising forward and rear arms, the former having holes to permit the attachment to a swingletree-clevis and said holes being in the rear of the pivotal connections of the bellcranks Ato said doubletree when the said bellcranks are in their normal position, and said rear arms having a series of notches in their outer edges, hooks adjustably arranged on said arms and fitting said notches, springs having their outer ends connected to said hooks, and means for securing the inner ends of said springs on the doubletree.

13. The combination, with a doubletree, of a box open at the top and bottom and fitting the forward and rear edges of the doubletree at its rear ends, transverse ribs or flanges provided on said box and adapted to fit correspondingly-arranged slots in said doubletree, and said box being normally narrower than said doubletree and adapted to be expanded to permit the entrance of said ribs into said slots.

14. The combination, with a doubletree, of bell-cran ks pivoted on the ends thereof, springs secured at their innerends to said doubletree, hooks provided on the rear arms of said bellcranks and connected with the outer ends of said springs,L and said hooks being arranged to wedge on said arms and hold said springs out of engagement therewith when said springs are swung forward to a position substantially in line with said doubletree.

IOO

ITO

IIS

secured at their inner ends to said doublel tree and having' their outer ends attached to IO said real'nrnis, substantially as described.

In witness whereof I have hereunto set my hand this 2d day of June, 1903.

ALMON J. GRAY.

In presence of- RIoiIARD PAUL, S. V. GRIFFIN. 

